Proficient in JavaScript (reading notes)

Type checking of variables

        // Detection Type        var str = "Hello world";         if (typeof str== "string") {// use typeof to determine an example of an object type                     }        if (str.constructor==string) { // use constructor properties to determine the type            of an object // The constructor property exists in each object and always points to the function that created it        }

Another example of using constructor

        function User () {        }        varnew  User ();         = = User); // true        var New me.constructor ();         = = You.constructor); // true

        //check a list of parameters with a list of variable types strictly        functionStrict (Types,args) {if(Types.length! =args.length) {Throw"Invalid number of arguments. Expected "+ Types.length +", received "+ Args.length +" instead. "; }             for(vari = 0; i < args.length; i++) {                if(args[i].constructor!=Types[i]) {                    Throw"Invalid argument type. Expected "+ Types[i].name +", received "+ Args[i].constructor.name +" instead. "; }}} strict ([String, Number, Array], ["MyTest", 12, [11, 22, 33]]);

The function of curry

Curry is a technique that transforms a function into a new, simplified (and less accepted) function by filling multiple functions into a function body.

        function addgenerator (num) {            returnfunction  (toadd) {                return num +  Toadd;}            ;        }         var addfive = addgenerator (5);        Alert (Addfive (4) = = 9);

Examples of using privileged methods

        function User (name,age) {            var year = (new Date ()). getFullYear ()-age ;              This function () {// Create a privileged method that can access the year variable, while itself belongs to the publicly accessible                return year ;}        }         var New User (' Angela ', 1989);         = = 26);

Examples of dynamic generation methods

        functionUser (properties) { for(varIinchproperties) {                (function(which) {varp =i; which["Get" + p] =function () {                        returnProperties[p]; } which["Set" + p] =function(val) {properties[p]=Val; }                })( This); }        }        varuser =NewUser ({name:"Angela", Age:26        }); Alert (User.Name==NULL);//true//name property does not exist because it is a private variable of a Property objectAlert (user.getname () = = "Angela");//true//Use the new GetName method to get this value this function is dynamically generatedUser.setage (22); Alert (User.getage ()= = 22);//true

Examples of static methods

        functionUser (name, age) { This. Name =name;  This. Age =Age ; }        varuser =NewUser (' Angela ', 26); User.cloneuser=function(user) {//Static Methods            return NewUser (User.Name, user.age);//Create and return a new user        }               varCloneuser =User.cloneuser (User); alert (cloneuser.name);//Angela

Browser rendering and sequence of operations

Detect if DOM is available

        functionDomready (f) {if(Domready.done) {//If the function is executed immediately after loading                returnf (); }            if(Domready.timer) {//If we have added a functionDomReady.ready.push (f);//add it to the list of functions you want to execute}Else{addevent (window,' Load ', isdomready);//Add Event Listener} domready.ready= [F];//initializing an array of functions to executeDomready.timer = SetInterval (Isdomready, 13);//Check if the DOM is available as quickly as possible        }        functionIsdomready () {//Check if DOM is operable            if(Domready.done) {//If we can determine that the DOM is available, ignore                return false; }            //check that several functions and elements are available            if(document&&document.getelementsbytagname&&document.getelementbyid&&document.body) {clearinterval (domready.timer);//Stop checking if it is availableDomready.timer =NULL; //executing a waiting function                 for(vari = 0; i < domReady.ready.length; i++) {domready.ready[i] (); }                //Records We've done hereDomready.ready =NULL; Domready.done=true; }        }

Xpath

Curry is a technique that transforms a function into a new, simplified (and less accepted) function by filling multiple functions into a function body.

Proficient in JavaScript (reading notes)